全文获取类型
收费全文 | 321篇 |
免费 | 32篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 15篇 |
2012年 | 20篇 |
2011年 | 16篇 |
2010年 | 7篇 |
2009年 | 13篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 10篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1995年 | 9篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 11篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1971年 | 1篇 |
1967年 | 4篇 |
1966年 | 3篇 |
1965年 | 2篇 |
1964年 | 1篇 |
排序方式: 共有353条查询结果,搜索用时 15 毫秒
61.
This paper reports the prevalence of chronic energy deficiency (CED) based on body mass index (BMI) and its relation to other adiposity measures namely, waist-hip ratio (WHR) and conicity index (CI) in some low socio-economic groups from South India. Two ethnic groups from each area type, namely, tribal, rural and urban areas, are included and samples of 646 men and 670 women belonging to six groups are selected on a multistage basis. Based on the measurements, BMI, WHR and CI are calculated. A considerable proportion of populations studied here experience CED. A higher proportion of women than men show CED. The BMI and WHR are slightly higher among men and WHR exhibits significant intersex difference. The CI is in expected ranges and all ethnic groups differ from each other in all measurements and indices. Age is strongly correlated with WHR and CI, but not with BMI. Both WHR and CI are influenced by BMI. BMI and sex are found to be significant contributors to the variation in WHR, and ethnicity also added to the variation in CI. The present study also concludes that adult malnutrition (as indicated by BMI) is spread to a considerable extent in these populations of low socio-economic status. It appears that the ethnic differences occurring in several measurements/indices reflect the economic and social conditions. 相似文献
62.
Prospero JM Blades E Naidu R Mathison G Thani H Lavoie MC 《International journal of biometeorology》2008,52(8):823-832
Asthma is epidemic in developed and developing countries including those in the Caribbean where it is widely believed that
African dust, transported in high concentrations in the Trade Winds every year, is a major causative factor. The link between
asthma and dust in the Caribbean is based largely on anecdotal evidence that associates sharp increases in the occurrence
of asthma symptoms with hazy conditions often caused by dust. Here we report on a 2-year study of the relationship between
the daily concentrations of dust measured in on-shore Trade Winds at Barbados and pediatric asthma attendance rates at Queen
Elizabeth Hospital (QEH). We looked for large increases in QEH daily attendances in relation to daily dust concentrations
as previously suggested by anecdotal observations. We could not find any obvious relationship although there may be more subtle
linkages between dust and asthma. Our measurements show, however, that the concentration of dust in the size range under 2.5 μm
diameter is sufficiently high as to challenge United States Environmental Protection Agency air quality standards for respirable
particles. Thus, African dust may constitute a health threat of a different nature, producing symptoms less obvious than those
of asthma. 相似文献
63.
Ch. Srinivas Ch.N.S. Sai Pavan Kumar B. China Raju V. Jayathirtha Rao V.G.M. Naidu S. Ramakrishna Prakash V. Diwan 《Bioorganic & medicinal chemistry letters》2009,19(20):5915-5918
The first stereoselective total synthesis of new natural amide alkaloids 1–3 have been achieved from commercially available starting materials. Wittig olefination, Sharpless asymmetric dihydroxylation, epoxidation, a trans regioselective opening of 2,3-epoxy alcohol, Horner–Wadsworth–Emmons (HWE) olefination and amide coupling are the key steps. The amide alkaloids 1–3 are evaluated for their anticancer activity against colon (HT-29), breast (MCF-7) and lung (A-549) human cancer cell lines for the first time. 相似文献
64.
65.
Pradip Bhattacharya Tamil Ganeshan Soumiyadeep Nandi Alok Srivastava Prashant Singh Mohommad Rehan Reshmi Rashkush Naidu Subbarao Andrew Lynn 《Journal of molecular modeling》2009,15(9):1013-1025
During thermal transition and variation of pH, structural properties of 35 proteins and their complexes (bound with substrate
and co-factor) were analyzed in detail. During pH alteration, these proteins were shown to have substantial differences in
conformations. pH conformers were analyzed in detail. Free energy and other energy parameters were also estimated for these
proteins at various pH and temperatures. Detailed structural analysis and binding interfaces of various substrates, inhibitors
and cofactor of these proteins were also investigated using docking and molecular dynamic simulation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
66.
Naidu BN Sorenson ME Matiskella JD Li W Sausker JB Zhang Y Connolly TP Lam KS Bronson JJ Pucci MJ Yang H Ueda Y 《Bioorganic & medicinal chemistry letters》2006,16(13):3545-3549
Stereoselective reduction of dehydroalanine double bond in nocathiacin I afforded the primary amide 2. Enzymatic hydrolysis of the amide 2 provided the carboxylic acid 3, which upon coupling with a variety of amines furnished amides 4-32. Some of these semi-synthetic derivatives have retained very good antibacterial activity and have improved aqueous solubility. 相似文献
67.
Venkata Ramana Naidu Rucha S. Deshpande Moinuddin R. Syed Piyush Deoghare Dharamvir Singh Pravin S. Wakte 《AAPS PharmSciTech》2017,18(6):2045-2054
Current endeavor was aimed towards monitoring percent weight build-up during functional coating process on drug-layered pellets. Near-infrared (NIR) spectroscopy is an emerging process analytical technology (PAT) tool which was employed here within quality by design (QbD) framework. Samples were withdrawn after spraying every 15-Kg cellulosic coating material during Wurster coating process of drug-loaded pellets. NIR spectra of these samples were acquired using cup spinner assembly of Thermoscientific Antaris II, followed by multivariate analysis using partial least squares (PLS) calibration model. PLS model was built by selecting various absorption regions of NIR spectra for Ethyl cellulose, drug and correlating the absorption values with actual percent weight build up determined by HPLC. The spectral regions of 8971.04 to 8250.77 cm?1, 7515.24 to 7108.33 cm?1, and 5257.00 to 5098.87 cm?1 were found to be specific to cellulose, where as the spectral region of 6004.45 to 5844.14 cm?1was found to be specific to drug. The final model gave superb correlation co-efficient value of 0.9994 for calibration and 0.9984 for validation with low root mean square of error (RMSE) values of 0.147 for calibration and 0.371 for validation using 6 factors. The developed correlation between the NIR spectra and cellulose content is useful in precise at-line prediction of functional coat value and can be used for monitoring the Wurster coating process. 相似文献
68.
Redd AJ Roberts-Thomson J Karafet T Bamshad M Jorde LB Naidu JM Walsh B Hammer MF 《Current biology : CB》2002,12(8):673-677
Phenotypic similarities between Australian Aboriginal People and some tribes of India were noted by T.H. Huxley during the voyage of the Rattlesnake (1846-1850). Anthropometric studies by Birdsell led to his suggestion that a migratory wave into Australia included populations with affinities to tribal Indians. Genetic evidence for an Indian contribution to the Australian gene pool is contradictory; most studies of autosomal markers have not supported this hypothesis (; and references therein). On the other hand, affinities between Australian Aboriginal People and southern Indians were suggested based on maternally inherited mitochondrial DNA. Here, we show additional DNA evidence in support of Huxley's hypothesis of an Indian-Australian connection using single-nucleotide polymorphisms (SNPs) and short tandem repeats (STRs) on the nonrecombining portion of the Y chromosome (NRY). Phylogenetic analyses of STR variation associated with a major Australian SNP lineage indicated tight clustering with southern Indian/Sri Lankan Y chromosomes. Estimates of the divergence time for these Indian and Australian chromosomes overlap with important changes in the archaeological and linguistic records in Australia. These results provide strong evidence for an influx of Y chromosomes from the Indian subcontinent to Australia that may have occurred during the Holocene. 相似文献
69.
Strontium–aluminium–bismuth–borate glasses (SAlBiB) doped with different concentrations of Ho3+ were prepared using conventional melt quenching technique and their structural and optical properties investigated. X‐ray diffraction and scanning electron microscopy analysis were used to study the structural properties. Optical properties were studied by measuring the optical absorption and visible luminescence spectra. The Judd–Ofelt (J‐O) theory was applied to evaluate J‐O intensity parameters, Ωλ (λ = 2, 4 and 6). Using J‐O intensity parameters, radiative properties such as spontaneous transition probabilities (AR), branching ratios (βR) and radiative lifetimes (τR) were determined. From the emission spectra, a strong green emission nearly at 549 nm corresponding to the transition, 5S2(5F4)→5I8 was observed. Emission peak positions (λP), effective bandwidths (Δλeff) and stimulated emission cross‐sections (σp) were calculated for the observed emission transitions, 5F3→5I8, 5S2(5F4)→5I8 and 5F5→5I8 of Ho3+ in all the glass matrices. Chromaticity color coordinates were calculated using the emission spectra. The experimental results suggest that SAlBiB glass matrix with 1.5 mol% of Ho3+ has better emission properties. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
70.
Breast cancer is one of the most common cancers among the women around the world. Several genes are known to be responsible for conferring the susceptibility to breast cancer. Among them, TP53 is one of the major genetic risk factor which is known to be mutated in many of the breast tumor types. TP53 mutations in breast cancer are known to be related to a poor prognosis and chemo resistance. This renders them as a promising molecular target for the treatment of breast cancer. In this study, we present a computational based screening and molecular dynamic simulation of breast cancer associated deleterious non-synonymous single nucleotide polymorphisms in TP53. We have predicted three deleterious coding non-synonymous single nucleotide polymorphisms rs11540654 (R110P), rs17849781 (P278A) and rs28934874 (P151T) in TP53 with a phenotype in breast tumors using computational tools SIFT, Polyphen-2 and MutDB. We have performed molecular dynamics simulations to study the structural and dynamic effects of these TP53 mutations in comparison to the wild-type protein. Results from our simulations revealed a detailed consequence of the mutations on the p53 DNA-binding core domain that may provide insight for therapeutic approaches in breast cancer. 相似文献